Biology in Focus, HSC Course Glenda Childrawi, Margaret Robson and Stephanie Hollis Blueprint of Life Topic 21: Reproductive Technologies

DOT POINT(s) identify how the following current reproductive techniques may alter the genetic composition of a population: artificial insemination artificial pollination Cloning (we will discuss this next lesson)

Introduction Selective breeding techniques are reproductive technologies that may be used to achieve hybridisation. Selective breeding can be thought of as a form of artificial selection imposed by humans, when they conduct deliberate crosses of living organisms to obtain a combination of desirable characteristics in the offspring. (This contrasts with natural selection where environmental conditions determine which individuals produce the most offspring.) en.wikipedia.org

Selective Breeding In Plants Selective breeding in plants is by means of artificial pollination. Records show that artificial pollination is not only a modern practice. It was used in ancient times—an Assyrian carving that dates back to 870 BCE shows the artificial pollination of date palms. evolution.berkeley.edu

Selective Breeding In Plants Artificial pollination was used by Mendel in his experiments with pea plants in the 19th century and was also used by scientists such as Farrer who were involved in hybridisation studies; it is still used today. In the past century, thousands of new breeds of plants have been created using artificial pollination. daughterofthesoil.blogspot.com

Selective Breeding In Plants This process involves removing the stamens of a flower and dusting the pollen onto the stigma of the same flower (self- pollination) or another flower (cross-pollination). This, like the other selective breeding processes, gives the breeder a greater degree of control over the breeding process.

Selective Breeding in Animals Selective breeding in animals involves mating a male and female with desirable characteristics in the hope that some offspring will inherit both characteristics. For example, crossing a male of the Friesian variety (known for the ability to produce large quantities of milk) with a Jersey cow (which produces creamy milk) will create some offspring who produce large amounts of creamy milk. dairycruelty.com.au

Selective Breeding in Animals Offspring that reflect this desirable trait are then selected for further breeding. In selective breeding, both parent individuals are different varieties of the same species, so the offspring produced are fertile.

Selective Breeding in Animals Disadvantages: The breeding of undesirable side effects. For example a physical disadvantage arises when Friesian cattle are crossed with Jersey cattle. Some of these hybrid cows have such large udders that they can hardly walk.

Selective Breeding in Animals Costs (time and money). Selective mating is time-consuming and costly. It involves the transport of large animals over long distances, risking putting them together with a breeding partner of the opposite sex, hoping they will not injure each other and then waiting for them to mate. To overcome these problems, a newer technology called artificial insemination was introduced. peonyden.blogspot.com

Artificial Insemination This process involves taking sperm from a chosen male and artificially introducing it into several selected females. This became widespread from the 1980s onwards, with the discovery of the effective storage and transport of sperm. evolution.berkeley.edu

Artificial Insemination The semen containing sperm may be removed from the male (using mechanical stimulation), and the fluid is first chilled and then frozen in liquid nitrogen for long-term storage and transported. newbornbaby.com.au

Artificial Insemination Advantages Transportation is easier Its cost effective It reduces the danger to animals of injury in transit or during mating. Many females can be inseminated and so one male can sire offspring with several females. Since the semen can be frozen indefinitely, a male can be dead but still produce offspring.

Artificial Insemination Artificial insemination is also being used in conservation, to increase the numbers of endangered species—Monash University PhD student Jonathan Daly conducted the first artificial insemination of a shark (he used a broad-nosed seven-gill shark as a model species) to try to develop a technique to apply to grey nurse sharks whose numbers are dwindling on the east coast of Australia.

Artificial Insemination Myzuri, a male gorilla, is the first successful gorilla produced using this reproductive technology, which was carried out at Melbourne Zoo by Professor David Galloway of the University of Melbourne. cacb.wordpress.com

Artificial Insemination Disadvantages If many offspring arise from one father, it can lead to reduced genetic variability. Artificial insemination has become the principal assisted reproductive technology method for many types of cattle, sheep and pigs, as well as performance and sport horses around the world, including in Australia.

In Vitro Fertilisation(IVF) An egg is fertilised by a sperm outside the mother’s body (in an artificially created environment, e.g. a Petri dish) and then transferred into the biological mother, into a surrogate mother or frozen in liquid nitrogen for later transplantation or for use in scientific research. This method is often used in cases where there is decreased fertility in one or both of the parents.

Genetic Impact With the use of selective breeding techniques, humans alter the genetic composition of the breeding population by selecting organisms with traits considered by the breeder to be of advantage and carrying out controlled breeding of these organisms.

Genetic Impact The alleles that increase in frequency in the gene pool of the population are therefore those that have been selected by the breeder rather than by nature.

Genetic Impact The survival and reproduction of an individual within the population depend on the presence of alleles that enable them to increase the output of a product that is useful to humans, rather than alleles that increase their fitness in terms of suitability to the environment or reproductive success.

Genetic Impact There is a short-term increase in the genetic diversity when new hybrid species are created, but in the longer term the continued breeding of the same hybrid lines decreases genetic diversity. costofartificialinsemination.com

Genetic Impact Artificial pollination, insemination and in vitro fertilisation are technologies that do not allow humans to determine the exact combination of genes that will be passed on. Is there a way that we can??? evolution.berkeley.edu